Adult neurogenesis is the process of generating new neurons that become integrated into existing circuits after fetal and early postnatal development has ceased. In most mammalian species, adult neurogenesis only appears to occur in the olfactory bulb and the hippocampus, where neural stem/progenitor cells (NPCs) exist to create new neurons. In adult neurogenesis, microenviromental change is thought to provide a specific modulation for maintaining the multi-potent state of these NPCs. Neurodegeneration is driven by the activation of resident microglia, astrocytes, and infiltrating peripheral macrophages, which release a plethora of cytokines, chemokines, neurotransmitters, and reactive oxygen species. These endogenous factors cause further bystander damage to neurons and produces both detrimental and favorable conditions for neurogenesis. Interestingly, these endogenous factors also affect the proliferation, migration, differentiation, and survival of the NPCs, as well as regulate the incorporation of newly formed neurons into the brain circuitry. The unique profile of the endogenous factors released can vary the degree of neuroregeneration after neurodegeneration. This current review summarizes recent knowledge in the emerging field that is showing that adult neurogenesis is regulated by endogenous factors produced during neurodegeneration.
Recent studies have shown that the cellular immune response to the hypoxic microenvironment constructed by vascular remodeling development modulates the resulting pathologic alterations. A major mechanism mediating adaptive responses to reduced oxygen availability is the regulation of transcription by hypoxia-inducible factor 1 (HIF-1). Impairment of HIF-1–dependent inflammatory responses in T cells causes an augmented vascular remodeling induced by arterial injury, which is shown as prominent neointimal hyperplasia and increase in infiltration of inflammatory cells at the adventitia in mice lacking Hif-1α specifically in T cells. Studies to clarify the mechanism of augmented vascular remodeling in the mutant mice have shown enhanced production of cytokines in activated T cells and augmented antibody production in response to a T-dependent antigen in the mutant mice. This minireview shows that HIF-1α in T cells plays a crucial role in vascular inflammation and remodeling in response to cuff injury as a negative regulator of the T cell–mediated immune response and suggests potential new therapeutic strategies that target HIF-1α.
The microenvironment of solid tumors is characterized by low pO2 that is well below physiological levels. Intratumoral hypoxia is a major factor contributing to cancer progression and is exacerbated as a result of oxygen consumption by rapidly proliferating tumor cells near blood vessels, poor lymphatic drainage resulting in high interstitial pressure, and irregular blood supply through immature tumor vasculature. Hypoxia-inducible factor-1 (HIF-1) is the main transcription factor that regulates cellular responses to hypoxia. Cellular changes induced by HIF-1 are extremely important targets for cancer therapy. Therefore, targeting strategies to counteract HIF-1–active cells are essential for cancer therapy. In this study, we introduce a novel strategy for targeting HIF-1–active cells.
The tumor microenvironment, characterized by regions of hypoxia, low nutrition, and acidosis due to incomplete blood vessel networks, has been recognized as a major factor that influences not only the response to conventional anti-cancer therapies but also malignant progression and metastasis. However, exploiting such a cumbersome tumor microenvironment for cancer treatment could provide tumor-specific therapeutic approaches. In particular, hypoxia is now considered a fundamentally important characteristic of the tumor microenvironment in which hypoxia inducible factor (HIF)-1–mediated gene regulation is considered essential for angiogenesis and tumor development. Additional oxygen sensitive signaling pathways including mammalian target of rapamycin (mTOR) signaling and signaling through activation of the unfolded protein response (UPR) also contribute to the adaptation in the tumor microenvironment. This in turn has led to the current extensive interest in the signal molecules related to adaptive responses in the tumor microenvironment as potential molecular targets for cancer therapy against refractory cancer and recurrence in preparation for the aging society. Therefore, we should focus on the drug discovery for targeting the tumor microenvironment to develop tumor-specific cytostatic agents including angiogenesis inhibitors. In this paper, the development of hypoxia-selective prodrugs, HIF-1 inhibitors, and modulators of the tumor microenvironment will be discussed.
The hypoxia response regulated primarily by hypoxia-inducible factor (HIF) influences metabolism, cell survival, and angiogenesis to maintain biological homeostasis. In addition to the traditional transcriptional regulation by HIF, recent studies have shown that epigenetic modulation such as histone methylation, acetylation, and DNA methylation could change the regulation of the response to hypoxia. Eukaryotic chromatin is known to be modified by multiple post-translational histone methylation and demethylation, which result in the chromatin conformation change to adapt to hypoxic stimuli. Interestingly, some of the histone demethylase enzymes, which have the Jumonji domain–containing family, require oxygen to function and are induced by hypoxia in an HIF-1–dependent manner. Recent studies have demonstrated that histone modifiers play important roles in the hypoxic environment such as that in cancer cells and that they may become new therapeutic targets for cancer patients. It may lead to finding a new therapy for cancer to clarify a new epigenetic mechanism by HIF and histone demethylase such as JMJD1A (KDM3A) under hypoxia.
Flavangenol is the French maritime pine bark extract (PBE). It consists of a concentrate of pine bark constituents such as catechin, taxifolin, and proanthocyanidins. Recent studies have shown that PBE has a strong antioxidant effect and exerts ameliorative effects on cardiovascular, skin, cognitive, and menstrual disorders, as well as in the context of other diseases and disease processes such as diabetes and inflammation. We have also obtained evidence that Flavangenol suppresses nuclear factor-kappa B (NF-κB) activation and the subsequent various NF-κB–induced gene expressions such as those of adhesion molecules and endothelin-1 in cultured vascular endothelial cells and that the antihypertensive effect of Flavangenol on deoxycorticosterone acetate–salt hypertensive rats is attributable to both its antioxidative property–related protective effects against endothelial dysfunction and the endothelium-dependent vasorelaxant effect, which is mediated by endothelial nitric oxide synthase activation. Furthermore, Flavangenol showed a renoprotective effect on ischemia/reperfusion-induced acute kidney injury in rats. These findings suggest that Flavangenol supplementation may be a promising candidate for the improvement of endothelial dysfunction and the prophylactic treatment of vascular diseases.
Quercetin, a member of the bioflavonoids family, has been proposed to have anti-atherogenic, anti-inflammatory, and anti-hypertensive properties leading to the beneficial effects against cardiovascular diseases. It was recently demonstrated that quercetin 3-O-β-D-glucuronide (Q3GA) is one of the major quercetin conjugates in human plasma, in which the aglycone could not be detected. Although most of the in vitro pharmacological studies have been carried out using only the quercetin aglycone form, experiments using Q3GA would be important to discover the preventive mechanisms of cardiovascular diseases by quercetin in vivo. Therefore we examined the effects of the chemically synthesized Q3GA, as an in vivo form, on vascular smooth muscle cell (VSMC) disorders related to the progression of arteriosclerosis. Platelet-derived growth factor–induced cell migration and proliferation were inhibited by Q3GA in VSMCs. Q3GA attenuated angiotensin II–induced VSMC hypertrophy via its inhibitory effect on JNK and the AP-1 signaling pathway. Q3GA scavenged 1,1-diphenyl-2-picrylhydrazyl radical measured by the electron paramagnetic resonance method. In addition, immunohistochemical studies with monoclonal antibody 14A2 targeting the Q3GA demonstrated that the positive staining specifically accumulates in human atherosclerotic lesions, but not in the normal aorta. These findings suggest Q3GA would be an active metabolite of quercetin in plasma and may have preventative effects on arteriosclerosis relevant to VSMC disorders.
Arachidonic acid (ARA) and docosahexaenoic acid (DHA) are major constituents of cell membranes and play important roles in preserving physiological and psychological function. Recently, data from several studies have indicated that impairments in long-term potentiation (LTP), the process underlying plasticity in synaptic connections, are associated with a decrease in membrane ARA and DHA in aged rats; and treatment of aged rats with either of these polyunsaturated fatty acids (PUFAs) reverses age-related decrease in LTP and the decrease in membrane fatty acid concentration. This review focuses on our recent findings concerning the effects of ARA and DHA on the age-related decline in the function of the brain and cardiovascular system. ARA supplementation decreased P300 latency and increased P300 amplitude of event-related potentials in healthy elderly men. Cognitive impairments in patients with mild cognitive impairment (MCI) and patients with organic brain lesions were significantly improved with ARA and DHA supplementation. ARA and DHA supplementation also increased coronary flow velocity reserve in elderly individuals; this suggests beneficial effects of PUFAs on coronary microcirculation. In conclusion, ARA and DHA may be beneficial in preventing and/or improving age-related declines in brain and cardiovascular system function.
The merits and demerits of food with health claims for the prevention of metabolic syndrome (MS) are reviewed. One major underlying cause of MS is obesity. Diet and lifestyle changes remain the cornerstones of therapy for obesity, but resulting weight loss is often small and long-term success is extremely uncommon and disappointing. Many anti-obesity drugs have been associated with unintended therapeutic outcomes. Currently, only one drug (mazindol) is approved in Japan for short-term treatment of individuals with a BMI over 35 kg/m2. Treatment with orlistat with dietary modification, caffeine, or protein supplementation; consuming a low-fat diet; adherence to physical activity routines; prolonged contact with participants; problem-solving therapy; and the alternative treatment of acupressure are efficacious in reducing weight regain after weight loss treatment. Because obesity is highly stigmatized, any effective treatment should be made available to improve quality of life and self-image. Therefore, it is necessary to provide information to consumers through the media concerning 1) basic knowledge about health foods and laws concerning them, 2) scientifically based information on safety/effectiveness of health foods and food elements, and 3) reports on health disturbances associated with health foods around the world.
The effects of AS1892802, a selective Rho-associated coiled coil kinase (ROCK) inhibitor, on knee cartilage damage and pain behavior were examined in a rat model of osteoarthritis (OA). Monoiodoacetate (MIA) was intraarticularly injected into the right knee joints of rats. ROCK I and II mRNA levels increased in knee joints of MIA-injected rats. Our newly synthesized ROCK inhibitor, AS1892802, was injected into the ipsilateral knee or administered p.o. for 3 weeks. The compound dose-dependently and significantly inhibited of cartilage damage in the tibial plateau in a dose-dependent manner and decreased the weight distribution deficit associated with MIA injection. In addition, the compound also inhibited bradykinin induced pain responses in normal rats. In vitro, the compound could induce chondrocyte differentiation in a chondrogenic cell line and significantly inhibited IL-1β– or bradykinin-induced prostaglandin E2 production in a synovial cell line. AS1892802 prevents cartilage damage induced by MIA and has analgesic effects in rat pain models, suggesting that AS1892802 may be clinically useful for the treatment of OA. [Supplementary Figure: available only at http://dx.doi.org/10.1254/jphs.10319FP]
Polymorphisms at codons 49 and 389 of the β1-adrenergic receptor gene have been shown to alter the receptor function in vitro, whereas it remains controversial whether they influence the response to β-blocker in vivo. In the present study, we investigated whether these polymorphisms influence the acute changes of heart rate and blood pressure induced by the β1-adrenergic receptor–selective blocker atenolol in healthy young Japanese. A double-blind study was conducted with 307 subjects randomly allocated 2:1 to atenolol (50 mg) or placebo groups. Heart rate and blood pressure were significantly reduced after administration of atenolol in comparison to the placebo. In 207 subjects allocated to the atenolol group, the numbers of Ser/Ser, Ser/Gly, and Gly/Gly allele carriers for codon 49 were 159, 46, and 2, respectively; and those of Arg/Arg, Arg/Gly, and Gly/Gly for codon 389 were 129, 66, and 12, respectively. No significant association was identified between the changes in heart rate or blood pressure and either of the two polymorphisms. There was also no difference in the changes in heart rate or blood pressure among the diplotypes. The results of the present study do not support clinical use of genotyping for these polymorphisms to predict responses to β-blockers.
Mast cells play a pivotal role in IgE-mediated allergic responses. Development of specific inhibitors against FcεRI-associated proximal signaling molecules in mast cells may represent a promising therapeutic strategy for allergic diseases. We examined whether a novel synthetic compound, 3-butyl-1-chloro-8-(2-methoxycarbonyl)phenyl-5H-imidazo[1,5-b]isoquinolin-10-one (U63A05), could suppress antigen-stimulated degranulation and cytokine secretion in mast cells and IgE-mediated passive cutaneous anaphylaxis (PCA) in mice. U63A05 reversibly and dose-dependently inhibited degranulation of rat basophilic leukemia (RBL)-2H3 mast cells and bone marrow–derived mast cells (BMMCs) stimulated by antigen (IC50 values for RBL-2H3 and BMMCs were 4.1 and 4.8 μM, respectively). The secretion of inflammatory cytokines was also suppressed in antigen-stimulated mast cells. However, degranulation by thapsigargin, a typical calcium inducer, was not inhibited by U63A05. U63A05 exerts its inhibitory effect, to the same extent as in degranulation, on the activating phosphorylation of Syk and downstream signaling molecules, including LAT and SLP-76. Further downstream, the activating phosphorylations of Akt, Erk1/2, p38, and JNK were also inhibited. Finally, antigen-stimulated PCA was dose-dependently suppressed in mice (ED50, 26.3 mg/kg). Taken together, the results suggest that U63A05 suppresses the activation of mast cells and the mast cell–mediated allergic response through the inhibition of Syk activation in mast cells.
Hyaluronan (HA) of high molecular weight is used in the treatment of osteoarthritis and rheumatoid arthritis by intra-articular injection. While HA has been shown to suppress nuclear factor (NF)-κB activation by proinflammatory cytokines and lipopolysaccharide (LPS), intracellular upstream events that cause NF-κB down-regulation in response to HA remain unclear. Thus, this study was performed to investigate the involvement of phosphoinositide-3-OH kinase (PI3K)/Akt in the inhibition of the LPS-activated NF-κB pathway by HA in U937 macrophages. In adherent U937 macrophage cultures, pretreatment with HA of 2700 kDa (1 mg/ml, 1 h) significantly inhibited interleukin-6 (IL-6) production by LPS (200 ng/ml, 24 h)-stimulated U937 cells. LPS (200 ng/ml) activated Akt and NF-κB, whereas HA (1 mg/ml) down-regulated LPS-stimulated phosphorylation of Akt and NF-κB. Inhibition studies using LY294002 (20 μM) revealed the requirement of the PI3K/Akt pathway for LPS-stimulated IL-6 production and NF-κB activation. Pretreatment with anti–intercellular adhesion molecule-1 (ICAM-1) antibody (20 μg/ml) reversed the inhibitory effects of HA on LPS-induced production of IL-6 and activation of Akt and NF-κB. Herein, we provided the first evidence that HA suppresses the LPS-activated PI3K/Akt pathway, leading to down-regulation of NF-κB with diminished IL-6 production through interaction with ICAM-1.
The aim of this study was to determine suitable culture conditions for maintaining the activity of cytochrome p450 (CYP) 3A4 and drug transporters in primary cultured human hepatocytes. Human hepatocytes were isolated using the two-step collagenase perfusion technique and were cultured with four different media, serum-free William’s E medium (serum-free WEM), WEM containing fetal calf serum (FCS-WEM), WEM with human serum (HS-WEM), and Lanford’s medium. The albumin levels were maintained for 7 days in hepatocytes. Although CYP3A4 mRNA levels gradually decreased from 3 days, CYP3A4 and hepatocyte nuclear factor-4α alpha protein levels and activities were maintained for 7 days in hepatocytes cultured with serum-free WEM and Lanford’s but not in those with FCS-WEM and HS-WEM. Furthermore, CYP3A4 protein levels were significantly increased by the addition of rifampicin and dexamethasone to the culture media, indicating that the induction potential was maintained. The protein levels of P-glycoprotein, multi-drug-resistance-2, and breast cancer-resistance protein were maintained for 7 days in all media. Serum-free WEM and Lanford’s also maintained protein levels of CYP2C19, CYP2D6, and organic anion transporter polypeptide in the hepatocytes. Serum-free WEM and Lanford’s may be appropriate culture media for maintaining CYP3A4 and drug transporter protein levels in primary cultured hepatocytes.
Involvement of secretory phospholipase A2 (sPLA2) in the stretch-induced production of untransformed prostaglandin H2 (PGH2) in the endothelium of rabbit pulmonary arteries was investigated. The stretch-induced contraction was significantly inhibited by indoxam, a selective inhibitor for sPLA2, and NS-398, a selective inhibitor for cyclooxygenase-2 (COX-2). Indoxam inhibited the RGD-sensitive-integrin–independent production of untransformed PGH2, but did not affect the RGD-sensitive-integrin–dependent production of thromboxane A2 (TXA2). These results suggest that the stretch-induced contraction and untransformed PGH2 production was mediated by sPLA2–COX-2 pathway, making it a new possible target for pharmacological intervention of pulmonary artery contractility.
Cigarette smoking is one of the factors causing accumulation of vascular smooth muscle cells (VSMCs) in atherosclerotic plaques. Changes in cell migration toward platelet-derived growth factor BB were investigated using a Boyden chamber after 48-h preincubation of GBaSM-4 VSMCs with nicotine or nicotine-free cigarette smoke extract (CSE). A nicotine concentration of 0.1 μM maximally promoted cell migration; 0.1% CSE also promoted cell migration, while high CSE concentrations damaged GBaSM-4 cells. Fetal bovine serum (FBS) long-depletion induced decrease in migration of GBaSM-4 cells. Our results suggest that nicotine and some CSE components can induce GBaSM-4 cell migration.